For example, Twisted Nematic (TN) mode liquid crystal display devices using nematic liquid crystals have been utilized. The TN mode liquid crystal display device includes a pair of substrates facing each other, and a liquid crystal layer interposed between the substrates, and is configured to drive the liquid crystal layer by generating an electric field between electrodes provided to the respective substrates. That is, the liquid crystal molecules of the liquid crystal layer are switched to point the substrates, depending on the presence or absence of the electric field between the substrates. However, the TN mode liquid crystal display devices have problems such as a slow response speed and a narrow viewing angle.
In view of this, in-plane mode liquid crystal display devices are known in which a pixel electrode and a common electrode are formed on the same substrate; a voltage is applied between the pixel electrode and the common electrode, thereby generating an electric field parallel to a substrate surface and driving the liquid crystal molecules in a plane parallel to the substrate surface.
In-Plane Switching (IPS) mode and Fringe Field Switching (FFS) mode are known as this in-plane mode. According to the IPS mode, to prevent the generation of display unevenness and reduce necessary voltages, a fine-toothed pixel electrode and a fine-toothed common electrode are combined and placed. According to the FFS mode, a pixel electrode and a common electrode for applying an electric field to a liquid crystal layer are located on different layers, with insulating films respectively interposed therebetween.
Here, these in-plane mode liquid crystal display devices have a problem in which thermal fluctuations of the liquid crystal molecules in the liquid crystal layer occur, and a contrast ratio is reduced due to the thermal fluctuations.
In view of this, to prevent a reduction in the contrast ratio, liquid crystal display devices including a polarizing layer are suggested. More specifically, a liquid crystal display device is disclosed which includes a pair of substrates, a pair of polarizing plates respectively placed on the pair of substrates, a liquid crystal layer sandwiched between the pair of substrates, an alignment film for aligning liquid crystal molecules in a predetermined direction, a pixel electrode and a common electrode formed at least one of the pair of substrates, for applying an electric field to the liquid crystal layer, and a polarizing layer having a uniaxial absorption anisotropy between the pair of polarizing plates. With this structure, it is possible to reduce a chromaticity change in a white representation and a black representation, and reduce luminance of the black representation to improve a contrast ratio (see, e.g., Patent Document 1).
Further, liquid crystal display devices are suggested which include two substrates facing each other, a liquid crystal layer interposed between the two substrates, an alignment film for aligning liquid crystal molecules in a predetermined direction, a color filter layer formed on at least one of the two substrates, and a polarizing layer located between the color filter layer and the liquid crystal layer, for compensating for depolarization of linearly polarized light in the color filter layer. The polarizing layer is a coating of molecules which are aligned and polymerized. With this structure, depolarization of linearly polarized light in the color filter layer is compensated, thereby reducing scattering of the depolarized light, and decreasing light transmission in the dark state. Consequently, a reduction in contrast ratio can be prevented (see, e.g., Patent Document 2).